IBC Demin Water vs On-Site Production

For many businesses, buying demineralised or deionised water in IBCs is the simplest way to get started. There is no plant to install, no treatment system to maintain, and no need to understand the finer points of resin exhaustion, membrane fouling, reject ratios or pretreatment. You order the water, store the container, connect a dispensing kit, and use it when required.

For low-volume or occasional use, that convenience can make perfect sense.

But once demand becomes regular, the economics can change quickly — and they tend to change quietly, spread across purchasing, goods-in, production and maintenance budgets, where no single person sees the total.

Why IBC water is such an easy place to start

Buying purified water in IBCs is attractive for good reasons, and it is worth being clear about them before looking at the alternative.

None of that stops being true as volumes grow. It just stops being the whole picture.

What IBC demin water actually is

In this context, IBC demin water usually means purified water supplied in a 1,000-litre intermediate bulk container. Depending on the supplier and grade it may be described as demineralised water, deionised water, DI water, purified water or ultra-pure water. Those terms are used loosely, and the quality behind them varies.

The spread is wider than most buyers realise. Some UK suppliers list standard grades at under 1.3 µS/cm, or under 1 µS/cm, with ultra-pure laboratory grades below 0.5 µS/cm. Others sell water advertised simply as deionised at around 10 µS/cm, with a stated maximum nearer 20. Those are not the same product, and they are not interchangeable in every process.

Typical uses across UK industry include:

The costs that never appear on the IBC invoice

The headline price of an IBC rarely reflects the true cost of using delivered purified water. A fair comparison has to include everything the site actually spends to get that water to the point of use.

The logistics are also more awkward than they first appear. A full 1,000-litre IBC weighs a tonne before the container is counted, and some suppliers cap tail-lift deliveries below a full container as a result. On a site without easy forklift access, dedicated storage or a reliable goods-in process, that has a real cost in time and disruption.

What producing water on site actually involves

Producing purified water on site means treating mains, borehole or process water through a system designed around your required flow rate and final water quality. A typical arrangement runs through these stages, though not every site needs every one:

The reason RO is usually placed ahead of ion exchange is economic as much as technical. Removing the bulk of the mineral load with a membrane means the resin is not being asked to do all the work, which extends resin life and reduces regeneration frequency. Where very low conductivity is needed, mixed-bed polishing downstream can take water well below 0.1 µS/cm.

Put simply: RO removes the bulk, and DI or mixed-bed finishes the job where higher purity is required. Using DI alone on raw feed water is almost always the more expensive route.

The comparison that matters is cost per usable litre

The question is not whether an RO/DI unit is cheaper than an IBC. It is what a usable litre costs over the next three to five years, at your actual usage, counting everything on both sides.

A worked example

Take a site buying four IBCs a month at £275 each, with one delivery per order at £59, all ex VAT. That is 48,000 litres a year.

On the invoice alone that is around 29p a litre. Counting the handling time it is closer to 31p. Neither figure includes emergency orders, storage space, quality testing or the cost of a production hold while a delivery is chased.

For comparison, mains water and wastewater together typically cost a UK business somewhere between £2.50 and £3.50 per cubic metre in 2026 — well under half a penny per litre before any treatment is applied. The gap between those two numbers is what pays for a treatment plant. Whether it pays for it quickly enough depends on your volume, feed water and required purity, which is exactly what the calculator below is for.

Work out your own numbers

Enter what you currently buy on the left, and the on-site assumptions on the right. Everything updates as you type, and nothing you enter is sent to us or stored — the calculation runs entirely in your browser. If you do not know a figure, leave the default in place and treat the result as a first indication rather than a quotation.

When buying IBC water is still the right answer

On-site production is not automatically the better option, and we would rather say so than sell a system that does not earn its place. Delivered water usually remains sensible when:

The strongest cases we see are sites where purified water is not just a consumable but part of the production process — chemical manufacturers dosing and diluting, metal finishing and coating lines needing consistent rinse quality, engineering businesses running cooling loops and test rigs, food and beverage producers with process and cleaning requirements, and laboratories with steady repeat demand.

Do you need RO, DI, or both?

One common mistake is treating demin water as a single fixed product. It is not, and the assumption is expensive in both directions. Some applications are perfectly well served by RO permeate. Others need DI polishing, microbial control, recirculation, point-of-use filtration or monitoring that can be recorded.

So the first question is not how much water you use. It is what quality the process actually needs. Useful specification points include:

If you currently buy IBC water, the supplier specification is a reasonable starting point — but it is not necessarily the answer. Your process may need less purity than the water you are buying, or it may need better control at point of use than the current arrangement provides. Both are worth knowing before anyone quotes anything. Our guide to what to gather before asking for a quote covers this in more detail.

The reliability question cuts both ways

IBC supply is reliable until it is not. A missed delivery, a delayed purchase order, a stock issue at the supplier, a transport problem or a sudden production increase can each create a bottleneck at short notice, and the site has very little control over any of them.

On-site generation changes the shape of that risk rather than removing it. You stop depending on deliveries and start depending on maintenance. A well-specified system should therefore include correct pretreatment, conductivity monitoring, sensible treated water storage, planned service intervals, a consumables and membrane replacement strategy, alarm points for quality deviation, and clear ownership of routine checks.

A neglected system creates its own problems. Membranes foul and scale, resin exhausts, filters block, and water quality drifts quietly if nobody is watching it. The goal is not to install equipment — it is to produce the required quality consistently, at the required volume, at a sensible lifetime cost. That is why a planned service arrangement should be part of the costing from the outset, not an afterthought once something fails.

The sustainability question, answered honestly

Moving purified water by road means moving a tonne of water per container, plus packaging, handling and empty-container logistics. Reducing those deliveries is a genuine benefit, and it shows up in Scope 3 reporting.

But on-site production is not impact-free, and it is worth being straight about that. RO systems use electricity and produce a reject stream. DI systems consume resin or regeneration services. Pretreatment uses salt, cartridges and chemicals. The honest comparison is between transport, packaging and delivery dependency on one side, and equipment responsibility, reject water, electricity and consumables on the other.

Which comes out better depends on volume, feed water quality, system recovery, energy use, discharge route and how well the plant is maintained. It is worth noting that chasing the highest possible recovery is not automatically the greener answer either — higher recovery can increase scaling risk, cleaning frequency, chemical use and energy demand. Sometimes a stable, slightly lower-recovery system gives better lifetime value.

Water costs are moving, and that changes the maths

The backdrop is shifting. Business water charges in England are set through Ofwat's PR24 price controls covering 2025 to 2030, which approved a £104 billion investment programme and an average increase in wholesale charges for business customers of around 42% before inflation across the five years — with the largest single jump landing in the first year, 2025/26.

The 2026/27 increases that took effect on 1 April 2026 were more modest, generally single-digit and smaller than the previous year across most regions. Two things are worth watching, though. Several wholesalers have unwound their Large User Tariff arrangements, which means high-volume sites in those regions can see higher than average increases. And the Competition and Markets Authority's redetermination process indicated prices could rise by roughly another 3% on average across the PR24 period.

At the same time, the Environment Agency has warned of a potential shortfall of around 5 billion litres a day in public water supply in England by 2055, with a further deficit forecast for the wider economy, unless action is taken.

For businesses buying IBC demin water, this matters twice over. The water used to produce that delivered product carries its own production, energy, treatment and logistics costs, which feed through to price. And a site producing water itself needs feed water and wastewater costs built properly into the operating model. Either way, water is becoming a cost worth understanding rather than accepting — a theme we explore further in the real cost of industrial water.

A practical review framework

If the calculator suggests the numbers are worth investigating, these are the seven things to establish before anyone specifies equipment.

So which is right for your site?

Buying IBC demin water is not wrong. For low, occasional or temporary demand it is often the most sensible option available — it avoids capital investment, simplifies responsibility and keeps flexibility.

But for manufacturers using purified water regularly, the numbers deserve a proper look. The true cost is not the figure on the invoice. It includes delivery, handling, storage, quality control, empty-container management and the risk of running out at the worst possible moment.

On-site RO, demineralisation or combined RO/DI systems can give a business real control over cost, quality and availability, and reduce dependence on regular deliveries. Whether that is worth doing depends on volume, required quality, feed water, site constraints, production risk and payback expectations.

For some sites, buying IBCs will remain the right answer. For others, the point at which producing your own water makes sense arrives sooner than expected — and it is usually cheaper to find that out with a calculator than with a year of invoices.